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CVE Record

CVE-2018-7843: A CWE-248: Uncaught Exception vulnerability exists in all versions of the Modicon M580, Modicon M340, Modic...

A CWE-248: Uncaught Exception vulnerability exists in all versions of the Modicon M580, Modicon M340, Modicon Quantum, and Modicon Premium which could cause denial of service when reading memory blocks with an invalid data size or with an invalid data offset in the controller over Modbus.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This vulnerability can crash or disrupt affected Schneider Electric Modicon controllers when they receive malformed Modbus memory-read requests. For operations using these PLCs, the business risk is process interruption rather than data theft. The source bundle does not provide CVSS scoring, patch details, or evidence of active exploitation.

Executive priority

Treat this as high operational priority for sites using affected Modicon PLCs. The main risk is denial of service to industrial controllers, which can affect production availability. Prioritize exposure review and vendor-guided remediation over emergency assumptions about active exploitation.

Technical view

CVE-2018-7843 is described as a CWE-248 uncaught exception in Modicon M580, M340, Quantum, and Premium controllers. Invalid data size or offset values while reading memory blocks over Modbus could trigger denial of service. The bundle does not include exploit maturity, firmware fixed versions, or detailed remediation text.

Likely exposure

Exposure is most likely where affected Modicon controllers have Modbus reachable from engineering workstations, plant networks, remote access paths, or improperly segmented IT networks. Internet exposure is not established by the source bundle.

Exploitation context

The vulnerability requires sending malformed Modbus memory-read activity to the controller. Talos published a vulnerability report, but the bundle does not show CISA KEV listing or other cited evidence of active exploitation.

Researcher notes

The source bundle supports affected products, root cause class, Modbus attack surface, and denial-of-service impact. It does not provide CVSS metrics, exact fixed versions, exploit status, or safe test cases. Avoid assuming more than vendor and Talos references establish.

Mitigation direction

  • Review Schneider Electric advisory SEVD-2019-134-11 for supported fixes and mitigations.
  • Restrict Modbus access to trusted engineering hosts and required network zones.
  • Remove any direct internet or broad corporate-network reachability to affected controllers.
  • Monitor plant networks for abnormal Modbus traffic and controller denial-of-service events.

Validation and detection

  • Inventory Modicon M580, M340, Quantum, and Premium controllers in operational environments.
  • Confirm which controllers expose Modbus and from which network segments.
  • Check Schneider Electric guidance for affected firmware and remediation status.
  • Review firewall rules, remote access paths, and engineering workstation access to PLC networks.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2018-7843 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aModicon M580 Modicon M340 Modicon Quantum Modicon PremiumModicon M580 Modicon M340 Modicon Quantum Modicon PremiumListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.